Sonoma County seems an odd place to find a blues legend. For the most part, it’s too chilly to sit on porches at night, it’s not very humid, and Memphis and New Orleans are a continent away. If I ever see him walking down the street, I’m going to ask harmonica master Charlie Musselwhite what it is about Geyserville that would lure a bred and buttered Mississippi bluesman out here for good. Was Tennessee too hot? Was the south side of Chicago too cold? At any rate, the inspiration for Blues Brothers’ Elwood and six-time Grammy nominee harps it up on Friday, July 20, at the Napa Valley Opera House. 1030 Main St., Napa. $20—$25. 8pm. 707.226.7372.